Determining approximate locations of network devices that are inaccessible to GPS signals

ABSTRACT

Methods, apparatus, and computer program products for determining approximate locations of network devices. Information is received concerning last known locations of portable network devices that attach to a network, and used to compute an approximate location of an obscured network device attached to the network. In some embodiments, the last known locations of the portable network devices may be determined using information from GPS satellites. The approximate location of the obscured network device may be used as the approximate location of other stationary network devices connected to the same network.

BACKGROUND

The invention concerns the field of network management, and moreparticularly concerns determining the locations of network devices thatare unable to access satellite positioning systems such as GPS becauseof shielding by buildings.

Internetworks and intranetworks have become exceedingly complex, andtherefore hard to manage. Thus, in order to enable a network operator tomanage such networks effectively, advanced network management systemsprovide the operator with a simplified graphical visualization of thenetwork. Traditionally, this is done using layout algorithms that placethe network devices in circles, in trees, and the like.

Technology has existed for some time to lay out network devices in sucha visual display using the latitudes and longitudes of the devices.However, in practice this has not been useful, because there has been noeffective way to gather the needed coordinates.

Although in principle a network device could be equipped with GlobalPositioning Satellite (GPS) capability to determine its location, GPShas a low RF link margin, and therefore cannot be used reliably todetermine locations of network devices that are used indoors.Unfortunately, many network devices of practical interest are indeedused indoors routinely. These include, for example, network devicesinside offices and laboratories, local area network (LAN) closets, datacenters, and so forth.

Of course, the needed coordinates could be manually determined andmanually entered into a network management database. Such a process,however, is not only impractical in large scale networks, it is alsotime consuming, error prone, and subject to constant revision as thelocations of network devices change.

Thus, there is a need for a way to automatically determine and track thelocations of network devices that are used in environments which areinaccessible to GPS signals, for the benefit of network managementsystems.

SUMMARY

Aspects of the invention include methods, apparatus, and computerprogram products for determining approximate locations of networkdevices. Information is received concerning the last known locations ofportable network devices that attach to a network, and used to computean approximate location of an obscured network device attached to thenetwork. In some embodiments, the last known locations of the portablenetwork devices may be determined using information from GPS satellites.The approximate location of the obscured network device may be used asthe approximate location of other stationary network devices connectedto the same network.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram that shows aspects of a portable networkdevice.

FIG. 2 is a block diagram that shows an exemplary network configurationsuitable for application of the invention.

FIG. 3 is a flowchart that shows aspects of a method for determining theapproximate locations of network devices according to the invention.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter, withreference to the accompanying drawings, in which illustrativeembodiments of the invention are shown. Throughout the drawings, likenumbers refer to like elements.

The invention may, however, be embodied in many different forms, andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that the disclosure will bethorough and complete, and will fully convey the scope of the inventionto those skilled in the art.

As will be appreciated by one of skill in the art, the present inventionmay be embodied as a method, apparatus, data processing system, orcomputer program product. Accordingly, the present invention may takethe form of an embodiment entirely in hardware, entirely in software, orin a combination of aspects in hardware and software referred to ascircuits and modules.

Furthermore, the present invention may take the form of a computerprogram product on a computer-usable storage medium havingcomputer-usable program code embodied in the medium. Any suitablecomputer-readable medium may be utilized, including hard disks, CD-ROMs,optical storage devices, and magnetic storage devices.

Computer program code for carrying out operations of the presentinvention may be written in an object oriented programming language suchas Java7, Smalltalk, or C++. However, the computer program code forcarrying out operations of the present invention may also be written inconventional procedural programming languages, such as the C programminglanguage. The program code may execute entirely on the user's computer,partly on the user's computer, as a stand-alone software package, partlyon the user's computer and partly on a remote computer, or entirely on aremote computer. The remote computer may be connected to the user'scomputer through a local area network or a wide area network, or theconnection may be made to an external computer, for example through theInternet using an Internet Service Provider.

The present invention is described below with reference to a flowchartillustration and block diagrams of methods, apparatus (systems), andcomputer program products according to embodiments of the invention. Itwill be understood that blocks of the flowchart illustration and blockdiagrams may be implemented by computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions and/or acts specified in the flowchart andblock diagram blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer readablememory produce an article of manufacture including instruction meanswhich implement the functions or acts specified in the flowchart andblock diagram blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions that execute on the computer or other programmableapparatus provide steps for implementing the functions and/or actsspecified in the flowchart and block diagram blocks.

FIG. 1 is a block diagram that shows aspects of a portable networkdevice 100. The portable network device 100 may be, for example, alaptop computer, a cellular telephone or other communicator, a personaldigital assistant, and the like. The portable network device is equippedwith a positioning receiver 110. In a preferred embodiment, thepositioning receiver 110 is a GPS receiver.

Because communication satellites are constrained by the availability ofelectrical power, the RF signals that they emit are typically weak.Thus, a satellite system such as GPS has a low link margin. Link marginindicates the RF power budget that is available beyond the level ofpower needed to provide a given minimal quality of communication over anunobstructed path in free space. The link margin is then proportional tothe greatest additional loss that may be inserted in a particularworking communication path by an obstruction such as, for example, abuilding. Because the link margin of GPS is unavoidably low, due tosatellite power constraints, the capability of GPS signals to penetratebuildings is quite limited. Moreover, a GPS receiver typically needsvisibility of at least three GPS satellites in order to make adetermination of location. Consequently, when the portable networkdevice 100 is brought indoors, the positioning receiver 110 may beunable to receive the signals it needs to compute the current locationof the portable network device 100.

As shown in FIG. 1, the portable network device may be further equippedwith a network adapter 160 such as a LAN card, and memory 120 withaddress space or registers for holding a device identifier (device ID)130, coordinates 140 such as latitude and longitude of the last knownlocation of the portable network device 100 as determined by thepositioning receiver 110, and the time at which the last known locationwas determined 150 (throughout, the term “location” refers to physicallocation). When the positioning receiver 110 is no longer able todetermine a location, the coordinates of the last known location of theportable network device 100 are loaded into the register 140, and thetime at which the last known location was determined is loaded into theregister 150. Thus, for example, when a GPS-equipped laptop computer isbrought into a building and consequently loses contact with therequisite GPS satellites, the coordinates of the last known location ofthe computer and the time at which GPS contact was lost may be recorded.

As shown in FIG. 2, the portable network device 100 may attach to anetwork 200 upon entering the building, through the network adapter 160.The description here uses an illustrative case wherein the network 200is a local area network. The invention is not so limited, however, andapplies as well to all kinds of networks, including, for example,Intranets and the Internet. As shown in FIG. 2, an obscured networkdevice 210 is connected to the network 200. For the purpose ofdiscussion, the obscured network device 210 is an indoor network devicewhose approximate location is to be determined. The term “obscured” isused with regard to the inaccessibility of the device to GPS signals.The obscured network device 210 may be, for example, a router, a LANhub, and the like.

As shown in FIG. 2 a stationary network device 220 such as aconventional desktop personal computer, and a network management system230, may be connected to the network 200. One purpose of the networkmanagement system 230 is to provide an operator with a visual orgraphical view of the various devices connected to the network 200. Thusthe purview of the network management system 230 is greatly simplifiedhere for purposes of discussion. It is not a requirement, of course,that the network management system 230 be connected to the manageddevices (the portable network device 100, the obscured network device210, and the stationary network device 220) by a single-hop LAN as shownin FIG. 2.

FIG. 3 is a flowchart that shows aspects of a method for determining theapproximate location of the obscured network device 210. The method maybe executed by, for example, the obscured network device 210 itself, orthe network management system 230, or the stationary device 220, or by anetwork server, or by any other device having suitable logic that isconnected to the network 200.

As shown in FIG. 3, the method awaits the attachment of the portablenetwork device 100 to the network 200 (step 300). After attachment (step310), the coordinates of the last known location of the portable networkdevice 100 are determined from its register 140 (step 320). The lastknown location may be provided by the portable network device 100 in anunsolicited manner as part of its bid to attach to the network 200,i.e., “pushed,” or may be solicited by, for example, the obscurednetwork device 210 or the network management system 230, i.e., “pulled.”

A determination is made as to whether any earlier information regardingthe location of the obscured network device 210 is known (step 330). Ifno earlier location information is known, the last known location of theportable network device 100 is used as the approximate location of theobscured network device 210 (step 340).

Otherwise (i.e., earlier information is known about the location of theobscured network device 210), a determination is made as to whether thelast known location of the portable network device 100 will be accepted(step 350). One purpose of this determination is to reject statisticaloutliers. For example, the last known location of the portable networkdevice 100 may be compared with an approximate location of the obscurednetwork device 210 determined by earlier iterations of the inventivemethod. If the last known location of the portable network device 100and the earlier determined location of the obscured network device 210are too far apart, the last known location of the portable networkdevice 100 may be rejected, whereupon the method returns to await theattachment of another portable network device to the network 200 (step300). In similar fashion, the time of the last known location from theportable network device's register 150 may be compared with the currenttime, and the last known location of the portable network device 100rejected if stale.

Otherwise (i.e., the last known location of the portable network device100 is accepted), the last known location may be recorded (step 360).Optionally, using the Device ID from the portable network device'sregister 120, an earlier report from the same portable network device100 may be overwritten. The approximate location of the obscured networkdevice 210 is then computed (step 370), using the newly acceptedinformation. The approximate location may be computed by, for example,averaging the newly accepted last known location together with aplurality of last known locations of a plurality of portable networkdevices recorded over time in earlier iterations of the inventivemethod. The approximate location of the obscured network device 210 maythen be assigned as the approximate location of stationary networkdevices that are connected to the same segment of the network 200 (step380), such as the stationary network device 220 shown in FIG. 2. Asshown in FIG. 3, the method returns to await the attachment of anotherportable network device to the network 200.

Although the foregoing has described systems, methods, and computerprogram products for determining the approximate locations of networkdevices that are inaccessible to GPS signals, the description of theinvention is illustrative rather than limiting; the invention is limitedonly by the claims that follow.

1. A method for determining approximate location of network devices,comprising: receiving information about last known locations of portablenetwork devices that attach to a network; and computing an approximatelocation of an obscured network device connected to the network, whichobscured network device is not one of said portable network devices thatattach to the network, using the last known locations of the portablenetwork devices; wherein the act of computing further comprisesdetermining whether to accept a last known location of a portablenetwork device for use in computing the approximate location of theobscured network device; wherein the act of determining furthercomprises comparing the last known location of the portable networkdevice with location information computed from a plurality of last knownlocations of other portable network devices which have attached to thenetwork.
 2. The method of claim 1, wherein the last known locations ofthe portable network devices are determined using information fromglobal positioning satellites.
 3. The method of claim 1, furthercomprising using the approximate location of the obscured network deviceas an approximate location of a stationary network device connected tothe network.
 4. The method of claim 1, wherein the act of determiningfurther comprises comparing a current time with a time at which the lastknown location of the portable network device was determined.